17 case class Sequ(v1: Val, v2: Val) extends Val

    17 case class Sequ(v1: Val, v2: Val) extends Val

    18 case class Left(v: Val) extends Val

    18 case class Left(v: Val) extends Val

    19 case class Right(v: Val) extends Val

    19 case class Right(v: Val) extends Val

    20 case class Stars(vs: List[Val]) extends Val

    20 case class Stars(vs: List[Val]) extends Val

    21 case class Rec(x: String, v: Val) extends Val

    21 case class Rec(x: String, v: Val) extends Val

    22    

    23    

    23 // some convenience for typing in regular expressions

    24 // some convenience for typing in regular expressions

    24 def charlist2rexp(s : List[Char]): Rexp = s match {

    25 def charlist2rexp(s : List[Char]): Rexp = s match {

    25   case Nil => ONE

    26   case Nil => ONE

    26   case c::Nil => CHAR(c)

    27   case c::Nil => CHAR(c)